ISSN 1311-8080 (PRINTED VERSION)

ISSN 1314-3395 (ON-LINE VERSION)

IJPAM: Volume 86, No. 5 (2013)

Young Key Kim1, Won Keun Min21Department of Mathematics
MyongJi University
Youngin, 449-728, KOREA2Department of Mathematics
Kangwon National University
Chuncheon, 200-701, KOREA

Abstract. The purpose of this paper is to introduce the notion of σ-structures and to investigate some properties for the structures. In particular, we investigate enlarging and quasi-enlarging operations induced by σ-structures.